1. Field of the Invention
This invention relates generally to land vehicles and more particularly to those of the wheeled type having tandem drive axles.
2. Description of the Prior Art
Presently, anti-roll devices are provided on single drive axles and those devices have been combined with resilient suspension members to provide vertical cushioning. Anti-roll devices are also provided for some tandem drive axles to provide some anti-roll stiffness but they may disturb the load sharing ability of the axles and they do not provide soft vertical cushioning for good ride characteristics. Insufficient anti-roll stiffness causes heavy duty vehicle tandem axles to have poor dynamic characteristics resulting in poor tracking and instability during turns. Such vehicles are generally of the class 8 type having high gross weight/high center of gravity characteristics and are primarily used for heavy hauling. Examples of such vehicles include ready mix, sanitation collection, coal haulers, construction, and the like.
In view of the above, it would be advantageous to provide a suspension system for heavy duty tandem axle vehicles having sufficient anti-roll characteristics and also having vertical softness or cushioning for good ride characteristics without disturbing desirable axle load sharing which overcomes the problems associated with the prior art.